功能金属-有机骨架材料的应用

金属有机骨架（Metal-Organic Framework,MOFs）材料由于其特殊的结构引起了科学家的广泛关注,它作为多孔材料与无机或有机的多孔材料相比具有特殊的优势,是目前新功能材料研究领域的一个热点。本文总结了金属有机骨架多孔材料在分离纯化、催化、微反应器、负离子交换、复合功能材料等方面的应用进展,并对这种新型多功能材料在设计、合成与应用方面的广阔前景作了展望。     

从分立多孔有机笼构建基于笼的三维框架材料显现出CO_2吸附增强

正多孔有机笼(Porous Organic Cage)是近年来出现的一类新型多孔材料~(1–4),与分子筛、金属有机骨架材料(MOFs)、共价有机骨架材料(COFs)等二维或三维框架多孔材料不同,多孔有机笼是分立的晶体材料,分立的构筑单元多通过弱相互作用堆积成有序多孔结构,其孔隙由笼内空腔和堆积贯通孔组成。与此同时,多孔有机笼还具备良好的可溶性,多孔有机笼在气体吸附,小分子选择     

骨架富含Si（4AI）结构的SAPO-34分子筛的合成及其对甲醇制烯烃反应的催化性能

通过在初始凝胶中加入HF合成了骨架富含Si（4AI）配位结构的SAPO-34分子筛。使用X射线衍射、扫描电镜、X射线荧光和核磁共振等表征手段研究了初始凝胶中HF的加入对合成SAPO-34分子筛的晶体结构、晶体形貌、元素组成以及骨架硅配位环境的影响结果表明,在初始凝胶中加入F离子后,合成的SAPO-34分子筛的晶体结构更加规整;随着初始凝胶中F离子含量的提高,合成的SAPO-34分子筛晶体骨架中Si（4AI）配位结构的数量增多,Si（n／AI）（n=3～0）配位结构的数量减少。将合成的SAPO-34分子筛催化剂用于甲醇制烯烃反应,结果显示,SAPO-34分子筛骨架中富含Si（4AI）配位结构可以有效提高反应产物中乙烯的选择性,同时能够延长催化剂的寿命。     

骨架富含Si(4Al)结构的SAPO-34分子筛的合成及其对甲醇制烯烃反应的催化性能

通过在初始凝胶中加入HF合成了骨架富含Si(4Al)配位结构的SAPO-34分子筛. 使用X射线衍射、扫描电镜、X射线荧光和核磁共振等表征手段研究了初始凝胶中HF的加入对合成SAPO-34分子筛的晶体结构、晶体形貌、元素组成以及骨架硅配位环境的影响. 结果表明,在初始凝胶中加入F离子后,合成的SAPO-34分子筛的晶体结构更加规整;随着初始凝胶中F离子含量的提高,合成的SAPO-34分子筛晶体骨架中Si(4Al)配位结构的数量增多, Si(nAl)(n=3～0)配位结构的数量减少. 将合成的SAPO-34分子筛催化剂用于甲醇制烯烃反应,结果显示, SAPO-34分子筛骨架中富含Si(4Al)配位结构可以有效提高反应产物中乙烯的选择性,同时能够延长催化剂的寿命.     

SAPO-5分子筛的结构和性能

AlPO_4-5是一种新型多孔磷铝分子筛晶体.由于骨架中不存在SiO_4四面体,PO_4~+AlO_4~-四面体交替排列,骨架呈电中性。Lok等首先报道了磷酸硅铝分子筛(SAPO)的合成.目前已有十几种元素同晶取代的AlPO_4-5分子筛.由于同晶取代,使得电中性的AlPO_4-5分子筛骨架呈电性和离子交换性,加之骨架本身所具有的良好热稳定性和多     

多孔材料化学:从无机微孔化合物到金属有机多孔骨架

本文主要从无机微孔化合物和金属有机多孔骨架的合成化学和结构化学这两方面来介绍多孔材料化学的研究进展。多孔材料是一类具有规则孔结构的固态化合物,它们在催化、分离、离子交换等工业领域有着广泛的应用。硅铝酸盐是最为人们所熟知的微孔分子筛,经过半个多世纪的发展,人们又相继开发出磷酸盐、砷酸盐、锗酸盐、亚磷酸盐、硫酸盐、亚硒酸盐以及金属硫化物等类沸石无机微孔化合物。近十多年来,配位聚合物与金属有机多孔骨架开始大量兴起,为微孔化合物的多样化与组成的复杂性增添了新的领域。     

钛硅分子筛（TS－1）的合成、结构表征及催化性能研究

在不同条件下成功地合成了钛硅分子筛ＴＳ－１，并利用ＩＣＰ－ＡＥＳ、ＸＲＤ、ＦＴ－ＩＲ、ＴＭＥ等手段对所获得的分子筛进行了表征，研究发现，ＴＳ－１分子筛中骨架钛与非骨架锐钛矿的相对含量、晶体结构、晶体粒子的大小、形貌特征等属性与分子筛的合成方法密切相关。并通过氯丙烯环氧化反应研究了获得的ＴＳ－１分子筛的催化活性与合成方法及其结构之间的相互关系。     

基于特征选择的决策树方法在磷酸铝AlPO4-5定向合成中的应用

分子筛类开放骨架材料的合成与结构关系研究对实现这类材料的定向合成起着至关重要的作用. 本文在建立开放骨架磷酸铝合成反应数据库的基础上, 提出了利用基于特征选择的决策树(C5.0)方法, 考察了不同反应条件(即各反应特征参数)对磷酸铝分子筛AlPO4-5生成的影响. 基于决策树模型, 利用8个反应特征参数,可以有效预测磷酸铝分子筛AlPO4-5的生成, 准确率达到88.18%, 接收者操作特性(ROC)曲线下面积(AUC)达到90%. 研究结果表明, 在众多的反应特征参数中, 有机模板剂的几何尺寸参数, 特别是模板剂的次长距离, 是影响AlPO4-5分子筛合成的重要因素.     

硅铝沸石分子筛晶化过程再思考

目前针对沸石分子筛的晶化过程已经进行了大量研究, 但是近年来硅铝分子筛的合成显示其晶化过程超出了传统的沸石分子筛晶化理论, 特别表现在硅铝沸石分子筛的模板作用、 水的作用以及沸石晶体之间的转化等. 本文讨论了上述作用的本质, 并通过研究模板法作用提出了无有机模板法合成硅铝沸石的策略, 通过了解水的作用提出了无溶剂法合成沸石分子筛, 通过表征沸石之间的转化过程发现不仅低骨架密度可以向高骨架密度晶体转化, 而且高骨架密度也可以向低骨架密度晶体转化.     

SCM-36分子筛纳米片用于乙烯和2,5-二甲基呋喃转化制可再生对二甲苯（英文）

分子筛是一类重要的结晶多孔材料,广泛应用于化学工业.开发新型分子筛特别是硅铝酸盐分子筛,一直是该领域的研究热点.分子筛的晶化过程一般需要结构导向剂的参与,包括碱(土)金属离子为代表的无机阳离子,有机胺或季铵盐为代表的有机物以及分子筛晶种.采用两种及以上结构导向剂的分子筛合成策略,具有调节分子筛骨架原子、晶体形貌和化学组成的作用,是开发新分子筛的有效手段.对二甲苯(PX)是合成对苯二甲酸乙二醇酯(PET)的重要原料.PX主要来源于石油资源,开发基于生物质原料生产PX的技术有利于缓解日益严峻的环境和能源危机.本文采用两种有机结构导向剂,以四甲基氢氧化铵(TMAOH)为有机结构导向剂,同时向体系中加入十六烷基溴化吡啶(C₁₆Py Br)或正辛基三甲基氯化铵(OTMAC),合成了一种新型铝硅酸盐分子筛,命名为SCM-36(Sinopec Composite Material No.36).SCM-36分子筛具有独特的X射线粉末衍射谱图(XRD)和纳米片状形貌.原位XRD结果表明, SCM-36分子筛在焙烧过程中由于晶胞收缩而导致衍射峰的偏移.扫描电子显微镜(SEM)、原子...     

Liquid Crystalline Materials for Biological Applications

Liquid crystals have a long history of use as materials that respond to external stimuli (e.g., electrical and optical fields). More recently, a series of investigations have reported the design of liquid crystalline materials that undergo ordering transitions in response to a range of biological interactions, including interactions involving proteins, nucleic acids, viruses, bacteria and mammalian cells. A central challenge underlying the design of liquid crystalline materials for such applications is the tailoring of the interface of the materials so as to couple targeted biological interactions to ordering transitions. This review describes recent progress toward design of interfaces of liquid crystalline materials that are suitable for biological applications. Approaches addressed in this review include the use of lipid assemblies, polymeric membranes containing oligopeptides, cationic surfactant-DNA complexes, peptide-amphiphiles, interfacial protein assemblies and multi-layer polymeric films.     

The Halogen Bond: An Emerging Supramolecular Tool in the Design of Functional Mesomorphic Materials

Owing to their dynamic attributes, non-covalent supramolecular interactions have enabled a new paradigm in the design and fabrication of multifunctional material systems with programmable properties, performances, and reconfigurable traits. Recently, the “halogen bond” has become an enticing supramolecular synthetic tool that displays a plethora of promising and advantageous characteristics. Consequently, this versatile and dynamic non-covalent interaction has been extensively harnessed in various fields such as crystal engineering, self-assembly, materials science, polymer chemistry, biochemistry, medicinal chemistry and nanotechnology. In recent years, halogen bonding has emerged as a tunable supramolecular synthetic tool in the design of functional liquid-crystalline materials with adjustable phases and properties. In this Concept article, the use of halogen bond in the field of stimuli-responsive smart soft materials, that is, liquid crystals is discussed. The design, synthesis and characterization of molecular and macromolecular liquid crystalline materials are described and the modulation of their properties has been emphasized. The power of halogen bonding in offering a large variety of functional liquid crystalline materials from readily accessible mesomorphic and non-mesomorphic complementary building blocks is highlighted. The article concludes with a perspective on the challenges and opportunities in this emerging endeavor towards the realization of enabling and elegant dynamic functional materials.     

Direct crystallization of silicate–phosphate glasses of NaCaPO4–SiO2 system

The subject of the study was silicate–phosphate glasses of NaCaPO₄–SiO₂ system which are precursors of glass–crystalline materials. Glass–crystalline materials of NaCaPO₄–SiO₂ system obtained via crystallization of glasses belong to a group of the so-called bioactive materials. In order to obtain glass–crystalline materials with pre-established parameters, it is necessary to conduct crystallization of glasses at specific conditions. In order to design direct crystallization process properly, it is necessary to know the structure and microstructure of the glassy precursor. Microscopic investigation showed that liquation takes place in all the studied glasses. Based on DSC examinations, it has been found out that crystallization of the glasses of NaCaPO₄–SiO₂ system is a multistep process. The presence of several clearly separated exothermic peaks in DSC curves of investigated glasses makes it possible to crystallize only the separated phase with the matrix remaining amorphous or vice versa. Conducted detailed X-ray and spectroscopic studies of the materials obtained by heating in a gradient furnace (in the temperature specified on the basis of DSC) showed that separated phase and matrix crystallizes separately. Therefore, bioactive glass–crystalline materials can be obtained due to the existence of the phase separation phenomenon and pre-established sizes of the crystalline phase.     

A Dual Threat: Redox‐Activity and Electronic Structures of Well‐Defined Donor–Acceptor Fulleretic Covalent‐Organic Materials

The effect of donor (D)–acceptor (A) alignment on the materials electronic structure was probed for the first time using novel purely organic porous crystalline materials with covalently bound two‐ and three‐dimensional acceptors. The first studies towards estimation of charge transfer rates as a function of acceptor stacking are in line with the experimentally observed drastic, eight‐fold conductivity enhancement. The first evaluation of redox behavior of buckyball‐ or tetracyanoquinodimethane‐integrated crystalline was conducted. In parallel with tailoring the D‐A alignment responsible for “static” changes in materials properties, an external stimulus was applied for “dynamic” control of the electronic profiles. Overall, the presented D–A strategic design, with stimuli‐controlled electronic behavior, redox activity, and modularity could be used as a blueprint for the development of electroactive and conductive multidimensional and multifunctional crystalline porous materials.     

Catalysis in Single Crystalline Materials: From Discrete Molecules to Metal-Organic Frameworks

Catalysis is one of the key techniques for people's modern life. It has created numerous essential chemicals such as biomedicines, agricultural chemicals and unique materials. Heterogeneous catalysis is the new emerging method with reusable catalysts. Among heterogenous catalysis patterns developed so far, single crystalline catalysis has become the promising one owing to its high catalytic density and selectivity resulted by the inherent porosity, orderliness of the lattices and permeability. These crystalline catalysts could be used in various reactions such as photo-dimerization, Diels-Alder reaction, CO₂ transformation and so on. In this review, we highlighted the reported works about the single crystalline catalysts. Both discrete small molecules and metal-organic frameworks (MOFs) have been used to prepare single crystals for catalysis. For discrete molecules based crystalline catalysts, coordinated and covalent molecules have been used. There were more catalytic modes in crystalline MOF catalysts. Three patterns were identified in this review: single crystalline MOFs i) without catalytic sites, ii) with inherent catalytic features and iii) with introducing catalytic units by post synthetic modification. Based on these examples, this review committed to provide the inspirations for the further design and application of single crystalline materials.     

A Dual Threat: Redox-Activity and Electronic Structures of Well-Defined Donor–Acceptor Fulleretic Covalent-Organic Materials

The effect of donor (D)–acceptor (A) alignment on the materials electronic structure was probed for the first time using novel purely organic porous crystalline materials with covalently bound two- and three-dimensional acceptors. The first studies towards estimation of charge transfer rates as a function of acceptor stacking are in line with the experimentally observed drastic, eight-fold conductivity enhancement. The first evaluation of redox behavior of buckyball- or tetracyanoquinodimethane-integrated crystalline was conducted. In parallel with tailoring the D-A alignment responsible for “static” changes in materials properties, an external stimulus was applied for “dynamic” control of the electronic profiles. Overall, the presented D–A strategic design, with stimuli-controlled electronic behavior, redox activity, and modularity could be used as a blueprint for the development of electroactive and conductive multidimensional and multifunctional crystalline porous materials.     

Advances in Metal‐Free Heterocycle‐Based Columnar Liquid Crystals

Liquid crystals are ordered soft materials formed by self‐organized molecules and can potentially be used as new functional materials for electron‐, ion‐ or molecular‐transport; optical; and bio‐active materials. In particular, the columnar liquid crystals are promising candidates used in various optical and electronic devices. For this purpose, design and synthesis of unconventional materials are essential. In this review, we have summarized several approaches for the synthesis of columnar liquid crystals composed of various heterocyclic systems. We also outline their liquid crystalline and other relevant properties, and their suitability for applications in diverse fields.     

Non-covalent side-chain polymers: design principles, functionalization strategies, and perspectives

Side-chain functionalized polymers have a profound impact on complex materials synthesis with a variety of applications ranging from liquid crystalline and electro-optical materials to drug delivery systems. In the last decade, the use of self-assembly towards the synthesis of side-chain functionalized polymers has been investigated extensively as a result of its modular character and ease of synthesis. This tutorial review describes recent advances in the literature and establishes basic design principles and synthetic approaches towards the fabrication of supramolecular materials that are based on side-chain functionalized polymers.     

光致变色液晶材料研究进展

本文介绍了液晶相态和光致变色的基本原理,液晶材料在光学领域中的应用,光致变色化合物的光异构化反应对液晶光学性质的影响,以及光致变色液晶材料制备的进展。参考文献53篇。     

Photoinduced alignment of polymerisable liquid crystals on photoreactive polymers containing 2,6-bis(benzylidene)-1-cyclohexanone units in the main chain

Photoreactive polymers containing 2,6-bis(benzylidene)-1-cyclohexanone (bisBC) units were synthesised and investigated as a photoalignment layer for polymerisable liquid crystals (PLCs) and liquid crystalline polymers (LCPs). The liquid crystalline materials were aligned homogeneously on the photoalignment layers in a wide range of irradiation dose of linearly polarised UV light (LPUVL). Specifically, for the photoalignment layer baked at 80°C, order parameters of the liquid crystalline materials were low due to the disturbance of oriented-photoreactive polymer caused by the contact with the solvent of liquid crystalline materials. However, the liquid crystalline materials were aligned homogeneously even at low irradiation doses on the thermally cured photoalignment layer baked at 180°C. In addition, the liquid crystalline materials were aligned perpendicular to the LPUVL electric field. The alignment mechanism is discussed by comparing the retardation of photoalignment layer with anisotropic polarisabilities of model molecules calculated by density functional theory (DFT). It is suggested that the liquid crystalline materials aligned along the unreacted chromophores in the photoreactive polymer.